Asphalt emulsions are widely used in roofing and other waterproofing applications. Unfortunately, most asphalt emulsions dry slowly, some requiring as long as a few weeks to dry before other coatings can be applied. This is inconvenient to both roofing contractor and building owner, since roofing projects cannot be finished quickly. Slow drying times also limit the times when such emulsions can be applied, since freshly-applied asphalt emulsion layers can be damaged or ruined by unexpected rain.
It is already known to speed drying times of asphalt emulsions by co-spraying an emulsion-breaking agent, such as calcium chloride, with the asphalt emulsion using a two component sprayer. See, for example, Usmani, Asphalt Science and Technology, 1997, Marcel Dekker, Inc., pp 297-306. This causes the emulsion to be broken, which in turn liberates its aqueous phase for rapid evaporation. This approach, which is often seen in the mining industry, is not commonly used in the roofing industry where the most popular spray equipment is capable of handling only a single component. Two-component sprayers are expensive and difficult to operate and hence beyond the purview of most roofing contractors.
It is also known to mix the emulsion-breaker with the asphalt emulsion before it is applied. See, p. 301 of the Usmani publication. This impacts the emulsion's working time and therefore is undesirable in commercial operations.
In accordance with this disclosure, this slow-drying problem is obviated by applying an emulsion-breaking agent to the surface to be waterproofed before the asphalt emulsion is applied, or by applying an emulsion-breaking agent to the asphalt emulsion after the emulsion is applied to the surface to be waterproofed, or both. By following this approach, the freshly-applied asphalt emulsion is broken and its aqueous phase liberated for evaporation as soon as the emulsion is applied, or promptly thereafter. However, because the emulsion breaker is applied separately from the emulsion, a two component sprayer is unnecessary. Therefore, this method can be easily practiced by the vast majority of roofing contractors using conventional spray equipment.
Thus, this disclosure provides a process for applying a waterproofing asphalt layer to a substrate comprising applying an asphalt emulsion to the substrate and contacting the asphalt emulsion with an emulsion breaker to liberate the aqueous phase of the emulsion and thereby speed emulsion drying, the emulsion breaker being applied to the substrate before the emulsion is applied to the substrate, or to the emulsion after the emulsion is applied to the substrate, or both.
In addition, this disclosure also provides a new building product for use in forming a waterproofing asphalt layer, the new building product comprising a fibrous or foraminous web or layer of material impregnated with an emulsion breaker.